Abstract.A linear program-assisted hybrid algorithm (GRASP-LP) is presented to solve a mixed-model sequencing problem in an assembly line. The issue of the problem is to obtain manufacturing sequences of product models with the minimum work overload, allowing the free interruption of operations at workstations and preserving the production mix. The implemented GRASP-LP is compared with other procedures through a case study linked with the Nissan' Engine Plant from Barcelona.Keywords: GRASP; Linear programming; Sequencing; Mixed-model assembly lines: Production mix preservation
PreliminariesFlexibility is the paradigm of the vast majority of the current production systems. Today production systems must be able to manufacture different versions of a product without physical changes at modules or workstations and with negligible setup times between different-type consecutive units; furthermore, they must respond quickly to any variation in the production plan. For this reason flexibility is what makes it important the sequencing problem.This flexibility is crucial at many manufacturing sectors, such as the Automotive, where production is carried on mixed-model assembly lines and the product mix changes frequently. This leads to the two main problems of this type of assembly lines: the balancing problem and the sequencing problem.Balancing problem appears in first place and it consists of assigning efficiently the set of assembly tasks for a product into the set of workstations arranged in series. The resulting line's configuration must meet the coherent order of tasks, and the set of restrictions linked with the task-attributes, such as the processing time, the required space and the involved risk [1].Once the line is configured and the demand plan is defined, the sequencing problem appears. This problem focuses on determining the manufacturing order of prod-